Is this a birth control side effect?

It could be from or from the pills.It is not uncommon to have some spotting while on the pills, even if you take them on a regular basis. You should not ovulate at all while on the pill, even while on the sugar pill. The bleeding while on the sugar pill looks like a period but is actually just withdrawal bleeding from the pills. This is why you hear the debate on why doctors think there is no real reason you need to have a "period" while on birth control.